1. Technical Field
The present invention relates to a coating liquid for ink jet and an ink jet recording method using the same.
2. Related Art
Ink jet recording methods are recording methods in which ink droplets are ejected and adhered on recording media such as paper to perform recording. Due to recent innovative advancement in ink jet recording technologies, ink jet recording methods are being increasingly employed in the fields of high-definition printing that have been realized by silver halide photos and off-set printing heretofore. With this advancement, inks for ink jet recording have been developed, which can realize image with gloss comparable to silver halide photos by ink jet recording using highly glossy recording media, i.e., special paper, comparable to the developing paper, art paper, and the like that have been used in the fields of silver halide photos and off-set printing. Moreover, inks for ink jet recording that can achieve image quality comparable to silver halide photos even when normal paper is used have also been developed.
Due to recent spread of image-forming technologies involving digital data, desk top publishing (DTP) has become popular in the fields of printing in particular. Even when recording is performed through DTP, a proof for correcting color is produced beforehand to confirm the gloss and color of actual recorded materials. Ink jet recording systems are being applied to outputting of such proofs. In DTP, high color reproductivity and high stability of the recorded materials are required, and therefore, special paper for ink jet recording is usually used as recording media.
Proof paper, which is special paper for ink jet recording, is prepared such that a print made therefrom has the same gloss and color as those of an actually output print on print paper. As such, the quality and material for special paper are appropriately adjusted according to the type of print paper but making special paper that is compatible with many types of print paper increases the production costs of print paper. Thus, for color proof usage, it is desirable from the technical viewpoint if ink jet recording can be performed on print paper rather than special paper. If samples made by performing ink jet recording directly on print paper without using special paper can be used as the final proof samples, possibly, the cost for proofing can be dramatically reduced from the economic viewpoint. Moreover, synthetic paper prepared by mixing inorganic fillers and the like with polyethylene resins or polyester resins and forming the resulting mixtures into films is widely used in the field of printing and is attracting attention as environmentally friendly products that have high recyclability. Thus, it is desirable from the environmental viewpoint if recording can be conducted on such synthetic paper.
Print paper is coated paper having a coating layer for receiving oil-based inks on its surface and is characterized in that the coating layer has poor ink-absorbing capability for aqueous inks. Thus, when aqueous pigmented inks commonly used in the ink jet recording are used, the inks exhibit low permeability into the recording medium (print paper), and bleeding, or aggregation unevenness or streak unevenness may occur in the images in some cases. As for these problems, addition of various components to inks is disclosed in JP-A-2005-194500, JP-A-2003-213179, JP-A-2003-253167, and JP-A-2006-249429.
However, in the case where the ink described in the Patent Documents above is used to record a color image on a low-ink-absorbing recording medium, in which the ink is a water-based ink, such as print paper, aggregation unevenness, streak unevenness, or the like may occur in color images on some occasions. Particularly, with non-ink-absorbing recording media having lower absorbency to a water-based ink than print paper (for example, plastic films made of a vinyl chloride resin or a polyester resin, and fabrics made of a vinyl chloride resin fibers or a polyester resin fibers), the problems as above may occur noticeably in some cases.
Regarding these problems, it can be considered, for example, that a receiving layer for receiving water-based inks may be provided on a non-ink-absorbing or low-ink-absorbing recording medium. Using a resin as the receiving layer can be considered, but depending on the type of the resin, the ink receivability cannot be satisfied in some cases. As for this problem, increasing the amount of the coating liquid to be attached on the recording medium can be considered.
However, with an ink jet recording system, when a coating liquid for forming a receiving layer is used to form a receiving layer, in a similar manner to water-based inks, the same problems as with the water-based inks, such as aggregation unevenness and streak unevenness, may occur in some cases, and this becomes noticeable particularly when the amount of the coating liquid to be attached to the recording medium increases. In the case where aggregation unevenness or streak unevenness occurs, the thickness of the receiving layer becomes non-uniform, and a region having a thin receiving layer has poorer ink receivability than a region having a thick receiving layer.
Furthermore, even though the aggregation unevenness or streak unevenness can be inhibited to form a receiving layer having sufficient ink receivability, water resistance of the image formed on the receiving layer is lowered, and thus, another problem that a good color image cannot be formed may occur in some cases.